1. Field of the Invention
The present invention relates an optical system that includes a variable focus lens.
2. Description of the Related Art
Conventionally, a variable focus lens that can change refractive power by controlling the shape of an interface between liquid media is known. In addition, increasing magnifications and furthermore downsizing of optical systems while reducing the amount of movement of lens groups is realized by using this variable focus lens in an optical system such as a zoom lens. The zoom lenses and image pickup apparatuses disclosed in Japanese Patent Laid Open No. 2005-84387 and Japanese Patent Laid Open No. 2005-292763 realize downsizing and, in addition, advantageously correct aberration by using such a variable focus lens.
However, in the zoom lenses and the image pickup apparatuses that have been disclosed in Japanese Patent Laid Open No. 2005-84387 and Japanese Patent Laid Open No. 2005-292763, when the refractive power of the variable focus lens varies because insufficient consideration has been given to achromatism, in particular, the fluctuation in chromatic aberration becomes large.